Fine-grain developers



Patented Apr. 5, 1%49 UNITED STATES PATENT QFFICE FINE-GRAIN DEVELOPERS No Drawing. Application May 11, 1945, Serial No. 593,322

2 Claims.

This invention relates to photographic developers and more particularly to developers which produce fine grain images.

A number of compounds have been found which when added to a photographic developer of moderate or low activity decrease the graininess produced by that solution. These generally are solvents for the silver halide such as thiocyanates, thiosulfates and thiourea. Paraphenylenediamine, when used as the developing agent produces fine grain images but the toxicity and staining propensity of this compound is objectionable. Certain addition agents such as ammonium salts and soluble amines have been suggested. However, ammonium salts are unstable in alkaline solution while amines do not produce as large a graininess reduction as desired and in excessive concentration may cause fog.

It is therefore an object of the present invention to provide novel addition agents for photographic developers. A further object is to provide addition agents for photographic developers which will produce a reduction in graininess of the image. A further object is to provide fine grain developers which will not result in excessive fog. A still further object is to provide a dry powder composition which may be mixed with water to produce a fine-grain developer having the properties referred to above. Other objects will appear from the following description of our invention.

These objects are accomplished according to our invention by using in the developer a suitable amine and a compound which yields an excess of chloride ions in solution. Such a combination. can effect a larger reduction in graininess than either alone and still maintain reasonable activity and emulsion speed.

Our developer comprises three essential ingredients, (l) a developing agent. (2) a soluble amine other than the developing agent, (3) a soluble chloride or compound which yields chloride ions in concentration in excess of the molar concentration of the amine. This may be achieved by (a) a relatively high concentration of a soluble chloride such as an alkali metal chloride or (b) the use of an amine hydrochloride plus a smaller concentration of the soluble chloride.

The developing agent may consist of any suitable silver halide developing agent such as monomethyl-p-amino phenol sulfate or hydroquinone.

Water-soluble amines of the following classes are suitable: Aliphatic amines, including primary alkyl amines such as methyl amine, butyl amine, alkylolamines such as ethanolamine and polyamines such as ethylene diamine, propylenediamine, and tetraethylenepentamine, and secondary alkyl amines such as diethylamine; primary aromatic amines such as meta-phenylenediamine and 2,4,6-triamino-toluene; secondary aromatic amines; amino alcohols such as 1,3-diamino propanol; amides derived from primary amines and carboxylic acids such as dilactyl ethylenediamine.

The chloride ion may be furnished by any compound capable of yielding chloride ions in the developer, These include simple chlorides such as sodium chloride and potassium chloride as well as compounds capable of releasing chloride such as hydrochloric acid. Part of the chloride ions may be added as an amine hydrochloride, the amine itself being either the one causing the graininess reduction or a non-reactive amine such as trimethylammonium chloride.

The most effective amines are the primary amines and non-volatile amines are preferred, although others may be employed if care is taken to prevent their escape during storage and use of the developer. Secondary amines may also be employed but their action is weaker and it is desirable to add the larger quantity of the chloride to supplement their action. Tertiary amines are of no value because their action is too weak. The optimum concentration of the primary and secondary amines is generally about 0.1 normal with reference to the amine although concentrations from about 0.05 to 4.0 normal are effective. In speaking of the normality of the amine, we are referring to the number of amino groups in the molecule. For example, a normal solution of a monoamine would also be a molar solution but a normal solution of a di--amine would be .5 molar, etc. The amines may be added either as the base or as salts, such as the sulfate, hydrochloride or other inorganic acid salt.

The most suitable chloride concentrations are from about 0.2 to 1.0 normal although the range of 0.05 to 4.0 normal may be employed in special cases.

Examples of suitable chlorides are (1) alkali metal chlorides such as potassium chloride, sodium chloride and lithium chloride (2) amine chlorides such as ethylenediamine dihydrochloride and triethylammonium chloride (3) chlorides of other metals such as magnesium chloride and zinc chloride provided the solution is properly compounded so that these do not precipitate (4) chloride-releasing compounds such as hydrochloric acid, hypochlorites, etc.

The following examples illustrate developing solutions containing the addition agents used according to our invention.

Example 1 A developer of the following composition was found to give a graininess reduction of 7 points on an empirical scale over the same developer without the ethylenediamine, when used for development of Kodak Plus X film.

Monomethylparaminophenol,

sulfate grams 5.0 Sodium sulfite (anhydrous) do 100.0 Ethylenediamine sulfate do 12.0 Sodium metaborate do 4.0 Potassium bromide do 0.25 Water to cc 1000.0

Increase in the ethylenediamine concentration had little effect on graininess, while the addition of sodium chloride had the following effect:

Total Graini- SodiumOhloride (Grams per Liter) ness Reduction Points Example 2 The following developer was found to give satisfactorily low raininess:

Monomethyl p-aminophenol sulfate -grams- 2 Hydroquinone do Sodium sulfite do 100 Sodium bisul-fite clo 2-amino-2-methyl-l-3 propane .diol do- 16 Sodium tetraphosphate do Magnesium chloride do 16 Water to cc 1000 Example 3 Thefollowing developer, dilutedl part to 1 part of water, was very effective in reducing graininess:

Monomethyl paraminophenol,

sulfate "grams" 8 Potassium sulfite do 76 Potassium metabisulfite do 17 Potassium chloride do Ethanolamine cc 18 Water to cc .1000

Example 4 The developer of the followingcompositiongave good reductions in graininess and fog-free images:

Monomethyl paraminophenol,

sulfate grams 5 Sodium sulfite (anhydrous) do 100 Sodium bisulfite do 1 Dilac'tyl ethylenediamine do 16 Sodium chloride do '20 Water to cc 1000 4 The following example illustrates a dry powder composition which may be used for the preparation of a fine-grain developing solution according to our invention.

Emample 5 Compartment A:

Moncmethyl p-aminophenol sulfate "grams" 5 Compartment B:

Sodium sulfite (anhydrous) grams Sodium bisulflte do 10 Sodium chloride do 20 2-amin-o-2-methyl 1-3 propanediol do 16 It will be understood that the formulas included herein are illustrative only and that our invention is to be taken as limitated only by the scope of the appended claims.

We claim:

1. A fine grain photographic developer having the fOllOWll'lg composition:

Monomethyl-p-amino phenol sulfate grams 5 Sodium sulfite (anhydrous) do 100 Ethylene diamine sulfate do 12 Sodium metaborate do 4 Potassium bromide do 0,25 Sodium chloride do 20 Water to cc 1000 2. A dry powder composition for the preparation of a, fine grain photographic developer by mixing with water to form one liter of developer, the following ingredients:

MonomethyLp-amino phenol sulfate -grams 5 Sodium sulfite (anhydrous) do 100 Ethylene diamine sulfate do 12 Sodium metahorate do 4 Potassium bromide do 0.25 Sodium chloride do 20 RICHARD W. HENN. JOHN I. CRABTREE.

REFERENCES CITED The following references are of record in the file of this patent:

OTHER REFERENCES Southworth, The Influence of the Acid Radical in Developers, Brit. Journ. of Plh0t., vol. 84, Nov. 5, 1937, pages 711 and 712 cited. 

